bq24079: R_TMR value

Jake Salmi

Part Number: BQ24079

Hi folks -

In the BQ24079 data sheet, we call out a recommended maximum R_TMR resistor value of 72k ohm. What happens if a larger value is used? Can a 75kohm value be used? 100kohm?

thanks,

Jake Salmi

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru 67476 points

Hello
I am checking on this one.
Do you need to increase the fast charge time?

Info from data sheet:
1.) Gnd TMR to disable timers
2.) Float to select internal default, 30min precharge and 5 hr fast charge
3.) Set range with 18k to 72k ohms, fast charge range 2.4hr to 9.6hr

0 Jake Salmi over 6 years ago in reply to Bill Johns

TI__Expert 7055 points

yes, the idea was to set the fast charge limit to 10 hours, slightly longer than 9.6 hrs nominal.

Thanks,
Jake

0 Ken Zhang over 6 years ago in reply to Bill Johns

TI__Intellectual 2325 points

Bill
the similar question about Rtmr is from my customer. customer wants to get >=20 hours safety timer. Is it possible to get 20Hour fast charge timer with 150Kohm?

0 Bill Johns over 6 years ago in reply to Ken Zhang

TI__Guru 67476 points

Hello Ken
20 hr is not an option but the timer can be disabled by connecting TMR to To get to ground.

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bq24079: R_TMR value